(a) Effects of degradation of ozone :
(1) UV-B damages DNA and proteins of living organisms causing mutation.
(2) It causes skin ageing, skin cell damage and skin cancer.
(b) CFCs release active chlorine which react with UV rays and degrade ozone releasing molecular oxygen. Depletion of ozone allows the entry of UV-B radiation to the earth which damages DNA causes mutation leading to the skin cancer in human and also rate of photosynthesis decreases in plants.